What happened
On March 22, 2018, a Piper PA-31-350 Chieftain, registration SE-FNE, operated by Jonair Affärsflyg AB, was on a business flight from Skellefteå, Sweden, to Kokkola-Pietarsaari, Finland. The flight, designated JON01, carried a two-person crew and four passengers. As the aircraft approached Kokkola-Pietarsaari, the crew noted significant icing conditions and expressed a desire to land immediately to avoid prolonged exposure to the weather.
At the time, runway maintenance was underway at the airport. The air traffic controller had authorized a friction-measuring vehicle to enter runway 19. While the crew was communicating with the controller regarding runway lighting and weather, the controller's radio was simultaneously broadcasting heavy noise from the ground vehicle's radio transmissions. This interference, combined with overlapping transmissions between ground and air traffic sectors, caused the controller to misinterpret the pilot's transmission. Believing the pilot had confirmed passing a specific waypoint, the controller issued a command for the aircraft to execute a go-around. However, the crew, focused on verifying runway lights, did not acknowledge the go-around instruction, creating a high-risk situation involving the aircraft and the maintenance vehicle on the runway.
The investigation
The investigation examined the sequence of events, the operational environment, and the technical systems in place at Kokkola-Pietarsaari. Investigators analyzed radio recordings, weather data, and the coordination between the flight crew, air traffic control, and ground maintenance personnel. The investigation also looked into the technical reliability of the communication equipment and the adequacy of the procedures used by the operator and the airport authorities.
Findings
- Radio interference from ground vehicle transmissions was clearly audible to both the pilot and the controller, disrupting critical communications.
- The air traffic control radio equipment was outdated and unable to clearly separate or monitor the aircraft's position during the final stages of the approach.
- Miscommunication occurred because the controller assumed a specific waypoint clearance had been acknowledged, while the pilot was actually attempting to confirm runway lighting settings.
- The maintenance vehicle operators were aware of the aircraft's intent to land but lacked clear instructions from the controller to vacate the runway.
- The crew's decision to attempt an immediate landing was driven by the need to escape worsening icing conditions.